This invention relates to composite plastic materials and specifically to a process for producing remoldable panels; the invention includes the panels obtained by such process, a plant for carrying out such process and the use of the panels for producing shaped articles.
Extrusion of thermoplastic polymer compositions is a well known and generally applied method for mass producing finished or semi-finished articles. Conventional thermoplastic compositions for extrusion processing contain a thermoplastic polymer as the main constituent. Inorganic or/and organic fillers may be used as minor constituents, i.e. in amounts of less than 40% by weight of the total composition. As the amount of filler increases it becomes increasingly difficult to process such compositions by extrusion. When using inorganic fillers, extrusion characteristics of the filler/resin composition can be improved by increasing the extrusion temperature. With organic fillers, however, this possibility is limited due to decomposition of most organic fillers, notably cellulosic materials at such elevated temperatures. Accordingly, it has generally been considered impossible to extrude compositions containing 40% by weight or more of such organic fillers and a thermoplastic polymer by normal extrusion methods.